[PATCH] D78933: [analyzer] RangeConstraintManager optimizations in comparison expressions

[Gábor Horváth via Phabricator via cfe-commits]

xazax.hun marked an inline comment as done.
xazax.hun added a comment.

Thanks!

I still have some nits inline, but overall the implementation looks good to me.
I think, however, that we should not only focus on the implementation but on the high-level questions. 
Is this the way forward we want? Can we do it more efficiently? What is the performance penalty of this solution?

The measurements I mentioned earlier about runtimes, node count and so on could help answer some of those questions.



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Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:587
+  // !=|1 |1 |* |* |0 |1 |0        |
+  // Columns stands for a preceding operator.
+  // Rows stands for a current operator.
----------------
I think it would be better to use slightly different terminology. Instead of preceding operator I would say something like "previously known fact". 


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Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:597
+  static constexpr size_t CmpOpCount = BO_NE - BO_LT + 1;
+  static const TriState CmpOpTable[CmpOpCount][CmpOpCount + 1] = {
+      // <      >      <=     >=     ==     !=    UnknownX2
----------------
I think this table together with the operations that transform between indices and operators could be factored out into a separate class. That would make this method slightly cleaner.


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Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:613
+
+  auto OP = SSE->getOpcode();
+
----------------
In LLVM we usually only use `auto` for iterators and to avoid repeating the type twice. Auto is ok above with the `dynamic_cast`, but here and some other places the type should be spelled out.


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Comment at: clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:668
+
+    auto BranchState = CmpOpTable[IndexSymOP][IndexPrevOP];
+
----------------
I think `IndexPrevOP` is confusing as the "previous" operation is not necessarily the previous operation we evaluated. In fact `IndexPrevOP` could have been evaluated any time in the past. We query the known facts that are known for the current state, I think this is what the names should reflect. I suggest to use `CurrentOP` and `QueriedOP`.


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Comment at: clang/test/Analysis/constraint_manager_conditions.cpp:184
+}
\ No newline at end of file

----------------
ASDenysPetrov wrote:
> xazax.hun wrote:
> > Nit: please add new line at the end of the file.
> I've added a new line and checked twice before creating a patch. But it didn't appear.
This looks good now. If it misses the new line there is a message saying that explicitly.


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https://reviews.llvm.org/D78933